I am currently creating a event map for our city and the aerial imagery has cars in the parking lot, I was wondering if there is a way to remove those cars from the image so it becomes a empty parking lot?
No, not within Pro. You would have to do that in Photoshop. One alternative might be to look through the ESRI Imagery Wayback for another image that has less cars in your area of interest. You can look at this Blog post about the Wayback and there's a link at the very bottom about using it in ArcGIS Pro
